The scattering phase shifts are invariant under unitary transformations of the Hamiltonian. However, the numerical solution of the scattering problem that requires to discretize the continuum violates this phase-shift invariance among unitarily equivalent Hamiltonians. We extend a newly found prescription for the calculation of phase shifts which relies only on the eigenvalues of a relativistic equal-time Hamiltonian and its corresponding Chebyshev angle shift. We illustrate this procedure numerically considering $\pi \pi$, $\pi N$ and $NN$ elastic interactions which turns out to be competitive even for a small number of grid points.

• Received 21 November 2019
• Accepted 17 January 2020

DOI:https://doi.org/10.1103/PhysRevD.101.036003